Self opening die head with improved ring-shaped latch unit



1950 R. M. STRICKLAND 7 SELF OPENING DIE HEAD WITH IMPROVED RING-SHAPED LATCH UNIT Filed Dec. 22, 1958 2 Sheets-Sheet 1 (r 30 40 3 W '10 /2'C5" INVENTOR ROYCE M. \STRICKLAND maz m q A4 ATTORNEYS.

Nov. 8, 1960 R. M. STRICKLAND 2,953,377

SELF OPENING DIE HEAD WITH IMPROVED RING-SHAPED LATCH UNIT Filed Dec. 22, 1958 2 Sheets-Sheet 2 INVENTOR Royce M. STRICKLAND AZIIAQWX A ATToR/VEYS'.

United States Patent Office 2,958,877 Patented Nov. 8, 1960 SELF OPENING DIE HEAD WITH IMPROVED RING-SHAPED LATCH UNIT Royce M. Strickland. New Haven, Conn., assignor to United-Greenfield Corporation, Chicago, 11]., a corporation of Delaware Filed Dec. 22, 1958, Ser. No. 782,033

7 Claims. (CI. 10-95) This invention relates to improvements in self-opening die-heads, and it relates more particularly to a type of die-head which is provided with a chaser-opening trip device located inside the die-head for direct engagement with the workpiece.

Certain threading operations require an accurate length of thread from the end of the workpiece. This means that the thread-cutting chasers must be withdrawn from the work at exactly the right time in order to provide the correct thread length. Tripping devices for terminating the threading operation are available for automatically opening the die-head after a predetermined amount of axial movement between the die-head and the workpiece. The most common type of tripping device is operated from outside the die-head by adjustably connecting a trip-member on the die-head to a part of the machine or spindle with which it is used. However, in some jobs the chucking or location of the workpieces makes it difficult in largescale production operations to cut accurate lengths of thread by means of such outside tripping arrangements. Tripping devices which engage the workpiece inside the die-head in order to take care of such a situation by referencing directly from the end of the workpiece have also been provided heretofore, but for one reason or another they have not been entirely satisfactory. One of the problems involved has been the extremely limited space available for such a device within the die-head. This makes it diflicult to provide an inside trip which will always function properly time after time in large-scale production Work.

Another major objection to some previous internal trip constructions has been the lack of run-by after the die-head is tripped. That is, in many cases the die-head will move forwardly a certain amount with respect to the workpiece, after the chasers are retracted. If the trip-member engaging the work is not permitted to move rearwardly with respect to the die-head by the amount which the die-head runs by the work after tripping, damage to the tripping mechanism and work can result.

It is, therefore, an object of the present invention to provide an inside trip for a die-head which can be relied upon for sensitive and accurate release of the threading chasers without fail even though under normal usage of the die-head the trip may be actuated many thousands of times. Another object is to provide an internal trip construction which will permit run-by after tripping, without danger of damage to the tripping mechanism. It is also an object of the invention to provide an inside trip for a die-head which is characterized by simplicity of construction, freedom from fault and ease of assembly and adjustment.

In general, the present invention comprises provision of aring-shaped latch-unit around the central shank of the main frame or skeleton of the die-head, said latch-unit being movable transversely of the shank and having a latching portion that is movable outwardly into latching engagement with a chaser-operating member of the diehead in order to releasably hold the operating member in its chaser-closing position. A trip member is provided within the shank of the skeleton in position to be moved axially thereof upon engagement with the workpiece. Such axial movement of the trip member applies a force outwardly against the inner surface of the latch-unit at a point diametrically opposite the latching portion of said unit in order to move the latching portion out of latching engagement with the chaser-operating member. This releases the chaser-operating member permitting the chasers to open.

In a particularly desirable embodiment of the invention, in which an outside trip may also be used to open the chasers, the latch-unit comprises two substantially semi-circular segments, one comprising the latching portion which holds the chaser-operating member in chaserclosing position, and the other comprising the opposite side of the latch-unit which is forced outwardly upon axial movement of the trip member. These semicircular segments are interlinked in such a manner that the latching segment will be positively withdrawn from its' latch-- ing position by the opposite segment in order to open the die-head by means of the inside trip, but when the die-head is opened by the outside trip the latching segment may be moved independently of the'inside trip mechanism. This permits installation of the inside trip mechanism in a wellknown sleeve-operated type of die-head construction shown in the patent to Breitenstein 1,639,719, which has been manufactured for many years by Geometric Tool Company of New Haven, Connecticut. Consequently, the inside trip arrangement of the present invention can be provided in self-opening die-heads of the type known as Geometric styles KD, KDS, and CK, without completely redesigning the die-head. This has great advantages in that much of the expense of redesigning and retooling a new die-head is avoided. Moreover, existing die-heads of this basic design can, if desired, be readily provided with an inside trip in accordance with the present invention, by simply altering some of the standard parts and replacing others.

These and other advantages and objects of the invention will become more apparent from the description hereinafter of a particularly desirable embodiment of the invention, reference being made to the accompanying drawings, in which Fig. 1 is a side elevation of a self-opening die-head in which the invention may be used;

Fig. 2 is a front end view thereof;

Fig. 3 is a view similar to Fig. 1 but with the die-head rotated in a clockwise direction, as viewed in Fig. 2, about its longitudinal axis, certain parts being cut away and shown in vertical section in order to reveal the latching mechanism;

Fig. 4 is a longitudinal section taken on the line 4-4 of Fig. 1 as viewed in the direction of the arrows;

Figs. 5, 6 and 7 are cross-sectional views taken on the lines 55, 66 and 77, respectively, of Fig. 4;

Fig. 8 is another view of the die-head shown in Fig. 1 but rotated 45 counterclockwise, as viewed in Fig. 2, certain parts being broken away and partially shown in longitudinal section in order to illustrate the chaseroperating mechanism; and

Fig. 9 is a perspective view of the latch-carrying ring removed from the die-head assembly.

In the drawings, the main frame or skeleton, so-called, comprises a cylindrical head-portion 12 with an integral hollow shank 14 extending rearwardly therefrom. The forward face of head-portion 12 is formed in this instance with four equally spaced radial slots 16, in each of which is mounted a radially movable chaser 18. Chasers 18 are retained in slots 16 laterally thereof by means of segmental plates 20, which are rigidly secured to the forward face of head-portion 12 by means of a plurality of screws 22 (Fig. 2). Each chaser 18 is urged outwardly toward its retracted position by a spring assembly 23 (Fig. 8) similar to that disclosed in the aforesaid patent to Breitenstein. In addition, each chaser is formed at its outer end with a sloping cam-surface 24 engaged by a similarly sloped cam-surface 26 formed adjacent thereto on the inner forward corner of a cupshaped, chaser-operating sleeve 28. Sleeve 28 is mounted on the skeleton for axial sliding movement with respect thereto and bears at its forward end on the periphery of the head-portion 12 and at its rear end on the periphery of a latch-carrying ring 30 mounted on the shank 14 of the skeleton.

Ring 30 is adjustably slidable axially on shank 14, with such adjustment being effected by an adjusting nut 32 threaded on shank 14. A pair of springs 3434 (Figs. 3 and 4) located on diametrically opposite sides of shank 14 in recesses 36 in the rear face of headportion 12 press against the front edge of ring 38 urging it rearwardly against adjusting nut 32. As best seen in Figs. 4 and 6, a keyway 31 is formed in the rear portion of sleeve 28 longitudinally thereof to receive a key 31a rigidly secured to the rear portion of ring 30, which is therefore restricted to axial adjustment only.

Latch-carrying ring 30 is provided midway between its ends with a deep circumferential groove 38 (Fig. 9) extending completely around its periphery. Groove 38 is adapted to receive a ring-shaped latch-unit indicated generally at 40 (Fig. 6). The upper portion of groove 38 as viewed in the drawings cuts entirely through ring 38 in order to provide a semicircular opening 42 to the inner side of ring 30 for a purpose which will be more apparent hereinafter. As may be seen in Fig. 9, formation of groove 38 and opening 42 leaves a relatively thin semi-cylindrical wall 44 at the base of circumferential groove 38. Wall 44 connects the front and rear cylindrical sections of ring 30, between which latch-unit 48 is held for movement transversely of the longitudinal axis of the die-head.

Latch-unit 40 consists of a pair of complementary, substantially semicircular segments 46 and 48 which, as best seen in Figs. 3 and 6, form an annulus having an outside diameter substantially equal to the outside diameter of the latch-carrying ring 30. As shown in Fig. 3, segments 46 and 48 are interconnected at their ends by means of hook-shaped fingers 50 and 52, respectively, which loosely interlock to permit relative lateral movement between said segments for a purpose to be described hereinafter.

The outer forward corner (lower front edge as viewed in the drawings) of the lower or latching segment 46 is adapted to engage with a substantially semicircular, eccentric latching shoulder 54 formed in the insidesurface of chaser-operating sleeve 28. Such latching engagement holds said sleeve in its forward chaser-closing position against the pressure of a pair of retracting springs 56-56 (Figs. 7 and 8) located at diametrically opposite sides of the die-head and having their forward ends seated in sockets (not shown), from which spring guide rods 58 extend, in the rear face of head-portion 12, the rear ends of retracting springs 56-56 being seated in sockets 59-59' in the forwardly facing internal shoulder 60 of sleeve 28. In addition, a pair of guide-posts 6262 located adjacent recesses 5959, respectively, in sleeve 28 (Fig. 7) project into recesses (not shown) in the rear face of head-portion 12 of the skeleton for the purpose of preventing rotation of sleeve 28 with respect to the skeleton.

The outside tripping means for disengaging the latch segment 46 from latching shoulder 54 in order to permit chasers 18 tomove radially outward from work-engaging position is similar to that shown in the above-mentioned patent to Breitenstein. This consists of an outside trip sleeve 64 which telescopes on the rear portion of chaseroperating sleeve 28 and is provided. h an internal C surface 66 adapted, when sleeve 64 is moved rearwardly on sleeve 28, to exert inward pressure on a steel ball 68, which is located in a radial passage 70 in the rear portion of sleeve 28. Ball 68 is positioned adjacent the mid-portion of latch segment 46 and bears on the periphery thereof in order to move it out of latching position upon rearward movement of trip sleeve 64. This permits chasenoperating sleeve 28 to move rearwardly against a stop 72 mounted on adjusting nut 32, and chasers 18 will retract outwardly from the work under the urge of their retracting springs 23.

Referring now more particularly to Fig. 4 and to the inside trip device to which the present invention is primarily directed, a tripping slide 88 fits within a hollow chamber 82 in head-portion 12 and shank 14 of the diehead skeleton for axial reciprocal movement therein upon engagement of the outer end of slide 80, or an extension thereof with the workpiece. Chamber 82 extends rearwardly to a point substantially behind adjusting nut 32 to permit tripping slide 88 to extend from a point in front of the foremost position of latch-carrying ring 38 to a point rearward of the 'rearmost position of adjust ing nut 32 for a purpose which will presently be apparent.- Rearward of chamber 82 is a short space 84 of reduced diameter which is adapted to receive and seat one end of a trip-return spring 86, the other end of which engages the rear end of tripping slide in order to urge the latter forwardly. A bore 88 of reduced diameter extends axially from reduced section 84 rearwardly through the balance of shank 14.

Tripping slide 80 is prevented from rotating within chamber 82 by a steel ball 90 located in a radial passage 92 in shank 14 of the skeleton and projecting into a semicylindrically shaped recess 94 of the same diameter as ball 91) formed longitudinally in the periphery of shank 14. Recess 94 is of uniform depth to permit ball 90 to ride in it when tripping slide 80 is moved axially, ball 98 and recess 94 acting not only to prevent rotation, but also to limit the axial movement of slide 80 within shank 14. Ball 90 is retained in passage 92 of shank 14 by the inner surface of wall 44 of latch-carrying ring 38. While ball 98 and recess 94 are in this instance located centrally of wall 44, it is obvious that they could be located at any point along the inner surface of wall 44 or, for that matter, some other means of keying tripping slide 88 with shank 14 could be provided if desired. The arrangement shown, however, provides a simple construction that has been found to be most satisfactory.

Latch camming means are provided on the tripping means and comprises another elongated recess 96 formed in the periphery of tripping slide 80 at a point diametrically opposite latch segment 46 and a steel ball 98. The steel ball 98 is located in a radial passage 100 in shank 14 adjacent the mid-portion of segment 48 of latch-unit 48 and is received within recess 96, the depth of which decreases toward the front end of tripping slide 80, so that as slide 88 is moved rearwardly by the workpiece, ball 98 is cammed outwardly. When this occurs,

ball 90 engages the inner surface of segment 48, and

moves it outwardly. This outward movement of segment 48 draws the latch segment 46 inwardly against the urging of a spring 188 and disengages the segment from the chaser-operating sleeve 28. This, as has already been described in connection with the outside tripping means, permits sleeve 28 to move rearwardly releasing chasers 18 from their work-engaging positions.

It will be noted from Fig. 4 that recess 96 inciudes, at its rear end, a substantially hemispherical portion of the same diameter as ball 98, and a substantially shallower front portion. The slightest rearward movement of tripping slide 80 causes ball 98 to be cammed outwardlyt Moreover, only a relatively small amount of movement of slide 80 is required to raise ball 98 far enough to draw latch segment 4-6 out of latching position. Since the front portion of recess 96 is somewhat elongated longitudinally of slide 80 and of uniform depth at this point,

slide 80 is capable of moving rearwardly even after the latch segment 46 has been tripped, thereby allowing for run-by in the automatic screw machine or turret lathe in which the die-head is installed. Both recesses 94 and 96 are therefore made long enough to allow for such run-by so that relative forward movement between the die-head and the work after the die-head is tripped does not damage the tripping mechanism. As has been noted hereinbefore, many prior inside trip devices have not provided for run-by with the result that the tripping member would frequently be forced against a solid part of the die-head before the relative forward movement of the work could be stopped. When this happened the diehead or workpiece could be seriously damaged. In the present instance, the recesses 94 and 96 are most desirably of the same length and in the same relative position axially of slide 80, so that both act simultaneously in cooperation with balls 90 and 98, respectively, to limit the forward and rearward movement of slide 88.

As may be seen in Fig. 6, segment 48 is free to move laterally under the force transmitted to it by ball 98 due to the fact that its inner cylindrical surface is eccentrically located toward its periphery such that when it is in its normal position in contact with the periphery of shank 14, as shown, space is provided between the periphery of segment 48 and chaser-operating sleeve 28 for segment 48 to move outwardly. The inner cylindrical surface of segment 48 is the same diameter as the outside diameter of shank 14, while the outside diameter of segment 48 is equal that of latch-carrying ring 30 and the inside diameter of sleeve 28. Consequently, when the die-head is tripped by the inside tripping means, segment 48 is moved by ball 98 into substantially full engagement with the inner surface of sleeve 28. In order to prevent segment 48 from tilting or rotating with respect to sleeve 28, it is keyed thereto by means of a key 102 which fits within keyway 31 of sleeve 28. Upon release of the inside trip, segment 48 is urged inwardly into normal seating engagement with shank 14 by means of springs 104-404 (Fig. 6) located in recesses in the periphery of segment 48 with a ball 186 positioned in the opening of each recess to provide sliding engagement with sleeve 28.

Latch se ment 46 is urged toward the latching position, in which it is shown in Figs. 3, 4 and 6, by the spring 108 which is located in a recess 110 midway be tween the ends of segment 46 on the inner surface thereof, the opposite end of spring 108 being seated in a shallow recess in the semicylindrical wall 44 of latchcarrying ring 30. Latch segment 46, unlike segment 48, is of uniform thickness substantially equal to or slightly less than the depth of the lower half of groove 38 adjacent wall 44. The outside diameter of latch segment 46, however, is equal to that of segment 48 so that when segment 46 is moved out of latching position, its periphery is substantially co-extensive with that of ring 30 in order to permit chaser-operating sleeve 28 to move rearwardly, as hereinbefore described. A keyway 112 is formed radially on the rear side wall of groove 38 in latch-carrying ring 30 and receives a key 114 projecting from the adjacent side of latch segment 46, whereby segment 46 is limited to radial movement within ring 30.

It will be noted that when latch segment 46 is in latching position as illustrated in the drawings, the interlocking portions of fingers 50 and 52 are engaged so that the slightest rearward movement of the internal tripping slide 80 is immediately transmitted to latch segment 46 through ball 98 and segment 48. However, since fingers 50 and 52 are substantially narrower in a circumferential direction than the notch 116 in segment 48 and notch 118 in segment 46, respectively, into which each of said fingers fits in the latching unit assembly, sufficient space is provided between the end of each finger and the opposite wall of notch 116 or 118 to allow segment 46 to be moved out of latching position by means of the outside trip without disturbing segment 48. Segment 48, there fore, moves only when actuated by the internal tripping slide to withdraw latch segment 46 inwardly from latching engagement with chaser-operating sleeve 28.

In order to adjust the point at which the die-head is tripped by means of the inside trip device, tripping slide 80 is provided with a central passage into which is threaded a rod-like trip-gage 122 extending axially of the die-head outwardly toward the chasers 18. The outer end of trip-gage 122 is provided with a socket 124 for a tool, such as a set-screw wrench, by which trip-gage 122 may be screwed in or out to the desired position so that it will be engaged by the work at exactly the right point in order to eifect release of the threading chasers by means of the self-opening mechanism of the die-head precisely when the desired length of thread has been cut. The opposite end of trip-gage 122 which projects into the bore 88 of shank 14 is formed with a pair of diametrically opposite V-grooves 126-126 extending longitudinally a predetermined distance from the end thereof, as may be seen in Figs. 4 and 5. Upon rotation of trip-gage 122, grooves 126126 alternately receive a ball 128 of a spring detent 130 located in a transverse passage in Hip ping slide 80 adjacent the rear end thereof. This provides a firm, yet resilient positioning or click adjustment for trip-gage 122, whereby the amount that tripgage 122 moves longitudinally can be accurately determined by the number of clicks of detent 130 in grooves 126 as the trip-gage is rotated. In addition, this arrangement provides means for determining the proper rotational position of trip-gage 122 with respect to a set-screw 132 threaded in a transverse passage in tripping slide 80 diametrically opposite detent 130, so that set-screw 132 can be brought into rigid locking engagement with one of grooves 126 in order to lock the trip-gage at any desired position. An aperture 134 is provided in the wall of shank 14 of the die-head skeleton adjacent set-screw 132, for the purpose of obtaining access by means of a tool to set-screw 132 so that it can be loosed when it is desired to adjust the position of trip-gage 122. It will now be understood that the trip slide 80 is made long enough to extend rearwardly of adjusting nut 30 so that access can be obtained to the internal trip set-screw 132 without disassembling the die-head.

In certain cases, where the die-head is large enough, the inside trip device of the present invention can be adapted to mount reaming and chamfering tools so that a pipe or tubing, for example, can he reamed, chamfered and threaded in one operation. The cutting tools for reaming and chamfering may be mounted in the outer end of trip-gage 122 in socket 124, or in a specially designed mounting socket. When the die-head is used in this manner, a heavier trip-return spring 86 than would normally be used is usually needed, in order to perform the inside cutting operation before the tripping slide 80 has reached its rearward limit as determined by the length of recesses 94 and 96 as hereinbefore described.

It will be seen from the foregoing description of one specific embodiment of the invention that the inside tripping mechanism is a simple and economical construction capable of adaptation with existing die-head constructions employing only an outside trip. When used in conjunction with an outside trip of the type herein disclosed, the present invention provides an important advantage in that the die-head can be converted to either inside or outside tripping by a few minor adjustments. In addition, due to the inherent simplicity of construction of the present inside trip, it is easy to set up the die-head for operation and is substantially trouble free.

What is claimed is:

1. In a self-opening die-head comprising a skeleton or frame having a hollow elongated shank, chasers mounted on said skeleton for reciprocal movement into and out of work-engaging position, and a chaser-operating member for moving said chasers into work-engaging position, the

combination comprising a ring-shaped latch-unit positioned around said shank and having a latching portion movable transversely outwardly with respect to the longitudinal axis of said shank into latching position with said chaser-operating member in order to releasably hold said member in its chaser-closing position, spring means re siliently urging said latch-unit into said latching position, tripping means mounted within the shank of said skeleton for releasing said chaser-operating member, said tripping means having a trip member movable axially of said shank and located with one end in position for engagement with the work, said tripping means having camming means engaging the inner surface of said latch-unit at a point diametrically opposite said latching portion and operable upon axial movement of said trip member to cam said latch-unit against the urge of said spring means and thereby to move said latching portion out of said latching position wherein said latch-unit comprises a pair of complementary segments, a first of said segments comprising said latching portion, the second of said segments being interlocked with the first so as to draw said first segment inwardly to unlatching position upon actuation of said trip member.

2. The combination defined in claim 1, wherein said tripping means includes a rigid ball confined within a radial passage in said shank between said trip member and the second segment of said latch-unit, said trip member having a depression of non-uniform depth axially of the die-head in which said ball is received.

3. The combination defined in claim 2, wherein said complementary segments of said latch-unit are held within a peripheral groove of a latch-carrying ring, the inner surface of which fits the periphery of said shank while the outer surface of said ring at least partially supports said chaser-operating member for sliding engagement thereof with respect to said latch-carrying ring, a portion of the peripheral groove of said latch-carrying ring in which said second segment is located being open at the inner surface of said ring in order to provide access for engagement of said ball with said second segment of said latch-unit.

4. The combination defined in claim 3, wherein an outside tripping sleeve is mounted in telescoping relation with said chaser-operating member whereby relative movement between said tripping sleeve and said chaseroperating member cams said first segment of said latchunit inwardly, and said segments of said latch-unit are interlocked at their ends in such a manner as to allow said first segment to move independently of said second segment.

5. The combination defined in claim 4, wherein said segments are provided with interlocking fingers at their ends, which fingers are in physical engagement when said latching portion or first segment is in latching position such that, upon outward movement of said second segment under the camming action of said inside tripping member and ball, said first segment is drawn inwardly by said second segment without any relative movement between said segments.

6. In a self-opening die-head comprising a skeleton or frame having an elongated shank, chasers mounted in said skeleton for reciprocal movement into and out of work-engaging position, and a chaser-operating member for moving said chasers into work-engaging position, the combination comprising an arcuate latch segment embracing said shank and movable transversely outwardly with respect to the longitudinal axis of said shank into latching position with said chaser-operating member in order to releasably hold said member in its chaser holding position, spring means resiliently urging said latch segment toward said latching position, a second arcuate segment movable transversely of and embracing said shank on the opposite side thereof from said latch segment, said segments being interlocked adjacent their ends so that said second segment can draw said latch segment inwardly to unlatching position, said segments being in full engagement when said latch segment is in latching position such that any movement of said second segment outwardly of said shank causes said latch segment to be moved inwardly, tripping means mounted within the shank of said skeleton for releasing said chaseroperating member having an elongated trip member positioned longitudinally of said shank with one end in 1 position for engagement with and movable axially by, the work, said trip member being provided with a cam surface cooperating with said second arcuate segment so as to move said second segment outwardly with respect to the shank of the skeleton upon axial movement of said trip member in one direction, thereby simultaneously withdrawing said latch segment from latching engagement with said chaser-operating member.

7. In a self-opening die-head comprising a skeleton or frame having an elongated shank, chasers mounted in said skeleton for reciprocal movement into and out of work-engaging position, and a chaser-operating member for moving said chasers into work-engaging position, the combination comprising an arcuate latch segment embracing said shank and movable transversely outwardly with respect to the longitudinal axis of said shank into latching position with said chaser-operating member in order to releasably hold said member in its chaser holding position, spring means resiliently urging said latch segment toward said latching position, a second arcuate segment movable transversely of and embracing said shank on the opposite side thereof from said latch segment, said segments being interlocked adjacent their ends so that said second segment can draw said latch segment inwardly to unlatching position, tripping means mounted within the shank of said skeleton for releasing said chaseroperating member having a trip member movable axially of said shank upon engagement with the work, said trip member being provided with a cam surface cooperating with said second arcuate segment so as to move said second segment outwardly with respect to the shank of said skeleton upon axial movement of said trip member, a trip return spring mounted within said shank urging said trip member forwardly of said die-head, said cam surface on said trip member providing stops limiting the axial movement of said trip member in both directions, the stop limiting rearward movement of said trip member being located such that said trip member is permitted to move rearwardly against said return spring a predetermined distance beyond the point at which said chaseroperating member is released by said latch segment.

References Cited in the file of this patent 

